Beatenbo's right, if you're heading directly to C-Springs, you can take US24 off of I-70 and avoid Denver altogether (and a bunch of extra miles). If you have to go to Denver, there's a few hills between Denver and C-Springs on I-25, but nothing to worry about, grade-wise. No matter where you roam up and down the state, the mountains of the Front Range do not start until you're well west of I-25.
For campgrounds in C-Springs, the only one we've stayed at so far has been Garden of the Gods in Manitou in April. It's a nice CG. http://www.coloradocampground.com/
C-Springs is great, with LOTS of stuff to do. If you haven't seen it, here's a photoshow of our adventure in April (we have young kids, so your itenerary may be different): http://www.brownland.org/travel/cosprings06/1.htm